Note 12 - Derivative Financial Instruments - Effect of Master Netting Arrangements on Derivative Assets and Liabilities in the Consolidated Statements of Condition (Details) - Interest Rate Swap [Member] - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Interest Rate Swaps, Gross Amount of Recognized Assets	$ 1,635,000	$ 15,961,000
Interest Rate Swaps, Gross Amount Offset in the Statement of Condition	0	0
Interest Rate Swaps, Net Amount of Assets Presented in the Statement of Condition	1,635,000	15,961,000
Interest Rate Swaps, Financial Instruments	0	0
Interest Rate Swaps, Cash Collateral Received	0	14,960,000
Interest Rate Swaps, Net Amount	1,635,000	1,001,000
Interest Rate Swaps, Gross Amount of Recognized Liabilities	20,147,000	2,239,000
Interest Rate Swaps, Gross Amount Offset in the Statement of Condition	0
Interest Rate Swaps, Net Amount of Liabilities Presented in the Statement of Condition	20,147,000	2,239,000
Interest Rate Swaps, Financial Instruments	15,607,000	0
Interest Rate Swaps, Cash Collateral Received	0	0
Interest Rate Swaps, Net Amount	$ 4,540,000	2,239,000
Interest Rate Swaps, Gross Amount Offset in the Statement of Condition		$ 0